I secretly gave my younger brother sex education without my husband's knowledge. (Kimiiro Kanon GVG-670)

Female teacher Kimiro Kanon lives with her husband and younger brother, and interestingly, she also serves as her younger brother's assistant homeroom teacher. One day, her younger brother wants to know the secrets of the female body. To fulfill her younger brother's wish, as his older sister and teacher, she uses her own penis to guide sex education, but unknowingly, it turns into incest...